Method of forming tubular bodies



March 24, 1936. A. A. SAALBACH METHOD OF FORMING TUBULAR BODIES FiledOct. 5, 1933 2 Sheets-Sheet 1 lN ENTOR A. A. SAALBACH METHOD OF FORMINGTUBULAR BODIES March '24, 1936.

Filed Oct. 5, 1933 2 Sheets-Sheet 2 IN ENTok ATTORNEYS Patented Mar. 24,1936 UNITED STAT OFICE METHOD OF FORMING TUBULAR BODIES ApplicationOctober 5, 1933, Serial No. 692,351

3 Claims.

The present invention relates to a method of forming true, tubularbodies and has particular reference to the reshaping of a non-circularfibre can body which has just been formed from layers of sheet materialand While the body is still in a moist and plastic condition and tocondition the moist body to utilize the drying strains and thecontracting action of drying so that the desired shape results in thefully dried body.

Laminated fibre tubular bodies are selected by way of example to setforth a preferred manner of carrying out the method steps of the presentinvention. In the formation of laminated bodies a strip or strips ofpaper or other fibrous material are wound around a forming mandrel toobtain the desired body form, this being done while the material is in amoist and plastic or g een condition, after which the bodies must bedried. In drying, internal strains are set up in the material (dryingstrains) efiective within and between the various layers and suchstrains in the usual tubular manufacture more or less distort the bodyout of its original and its desired shape.

The tendency of these drying strains in noncircular bodies and in thosehaving fiat sides is an unequal expansion of the corners and the sidesand the latter are pulled out and assume a curved shape when dry. Insome cases Where an exact shape is required it is necessary that thegreen body be held in molds or otherwise while drying so that it willretain its original shape within close limits.

An object of the present invention is the provision of a method ofreshaping or reforming fibre tubular bodies based on a relation to thedrying strains which will be set up in the body as it dries so that suchdrying strains will be utilized in bringing back the original bodycontour or shape in the completed body.

An important object of the invention is the provision of a method ofreforming green, fibre noncircular or oblong tubular bodies bystretching their corners and adjacent wall parts so that 4 when dryingthe stretched parts of the body are contracted just suificient to bringback the desired finished shape and size into the body as it becomesfully dried.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

Referring to the drawings:

Figure 1 is a part elevation, part sectional view of one form ofapparatus for carrying out the method steps of the invention;

Fig. 2 is an enlarged sectional view of a primary forming mandrel, beingtaken substantially along the line 2-2 in Fig. 1;

Figs. 3 and 4 are enlarged fragmentary sectional views of the reformingmandrel being taken substantially along the line 4- 1 in Fig. 1illustrating different positions of associated reforming elements;

Fig. 5 is a sectional view, taken substantially along the line 55 ofFig. 1; and

Fig. 6 is a cross sectional view of a finished or dried tubular body asmade according to the method of the present invention.

The first step in the present method may be considered to be theproducing of a formed green tubular body just built up in a plurality ofthicknesses from strips of paper or other fibrous material which havebeen wound while damp upon a revolving primary or forming mandrel. Alaminated body rectangular in shape and having rounded corners is hereinillustrated, the winding operation being a regular well known part ofthe usual fibre can manufacture. Where the bodies are relatively shortin body height more than one is wound on the mandrel at the same time,the drawings illustrating three such bodies. Three bodies are thusreceived for the succeeding reforming steps.

These formed and green bodies are slid endwise off the primary mandreland are moved endwise on to a secondary, stationary reforming mandrelWhere they are partially reformed by a stretching of the body stockaround the rounded corners while the straight sides of the body arepressed in. This stretching and pressing may be done in different waysas by rollers applied to the rounded corners but a preferred mode ofoperation, as illustrated in the drawings, is by the use of squeezerjaws pressed into the sides of the body leaving the corners free.

In the drying out of the reformed bodies, which takes place after thebodies are removed from the reforming mandrel, the shrinkage strains setup in the material contract the stretched parts and draw the sides ofthe body taut. This brings back the original rectangular shape of thebody, which when fully dried has straight non-bulging sides and roundcorners of the desired size.

The drawings show sufiicient of the principal parts of a mechanism tocarry out the method steps of the invention, the tubular bodies. I l(Figs. 1 and 2) being formed while moist in the usual manner as byWinding upon a rotatable forming or primary mandrel l2 of a suitabletube winding machine.

The forming mandrel l2 comes to rest after each winding operation and itis at such a time that the bodies H are slid endwise on to a stationaryreforming or secondary mandrel i5 supported at one end in the mandrel l2. Both mandrels l2, H? are of a cross section equivalent to the bodybeing formed and in the present instance are rectangular, having roundedcorners. Mandrel i5 is slightly smaller than mandrel l2 to permit easytransfer of the bodies from the latter on to the mandrel l 5.

The reforming mandrel l5 may be hollow to lighten its weight but isclosed at each end and is supported on a shaft H which projects beyondthe end of the mandrel H! in which it is tightly held by pins 1 9. Sincethe shaft turns with the forming mandrel l2 bearings 21, 23 are providedin the end pieces of the reforming mandrel 15 so that the mandrel IEwill not turn with the mandrel 12. A spacing washer 25 on shaft ll keepsthe ends of the two mandrels apart and a collar 21 on the outer end ofthe shaft keeps the reforming mandrel from coming ofi of the shaft. Themandrel !5 is held stationary and prevented from turning as will behereinafter fully described.

The mandrel I5 is provided with fluted sides, each of the four straightsides having a depression or wide groove 33 extending the full length ofthe mandrel and leaving the corners as rounded ridges 95. The green bodyis supported on these four ridges when first received on the mandrel andthe reforming or reshaping elements press inwardly against theunsupported body sides.

These elements comprise four squeezer blocks or jaws 31, each jaw beingformed on the inner end of a radially movable T sectioned slide 39(Figs. 1 and 2) Each slide operates within a T slot 4| cut into ahousing 43 formed as a part of a circular bracket frame d5 whichsurrounds the reforming mandrel I5. The bracket frame 45 is carried bysupporting legs 41 which rest on the top of a suitable frame 29 of theapparatus, being bolted thereto at 5|.

Each slide 39 is provided with a boss 53 (Fig. 1) which projects into aslot 55 formed .in an associated housing 3, and which carries a stud 51.A cam roller 59 is rotatably held on the stud 51 by a lock nut 6|. Eachroller 59 engages within an associated cam slot 63 cut in a ring plate65 which is mounted to turn in a circular groove 61 formed in thebracket frame 45. A ring washer 69 is held on the face of the bracketframe 45 by bolts 1i and confines the ring plate in its groove.

The ring plate 65 is positively oscillated within its grooved seat bymeans of a bifurcated bracket 13 (Fig. 5) which is secured by bolts 15to the face of the plate, the washer 69 being cut away at 71 to: giveclearance for the bracket. Bracket 13 extends out beyond the frame in alever arm 19 which is pivotally secured to a connecting rod 8| which maybe moved up and down in any suitable manner to impart the desiredoscillation to the ring plate 65.

The ring plate 65 is cut across in four cam slots 63 and a roller 59 islocated in each slot. When the ring plate is partially rotated all ofthe slides 39 and their jaws 37 move in or out in accordance with thedirection of movement of the ring plate. When the plate is movedcounterclockwise (Fig. 5) by a lifting of the rod 8| slides and jawsmove inwardly, the latter closing in on the green bodies I! positionedon the reforming mandrel I5, this being the positions shown in Figs. 4and 5. Such clamping action squeezes in and reforms the sides of thebodies and draws the body stock of the corners taut over the mandrelridges. This stretches the corners of the body.

The reforming operation takes place during the rotation of the formingmandrel I 2 as it winds the next set of bodies. The squeezer jaws 31held to hold the reforming mandrel l5 stationary and against rotation atsuch time and it is only after the forming mandrel has completed thewinding and comes into its rest period that the squeezer jaws 31 arereleased. The new set of three bodies H just formed are then moved on tothe reforming mandrel and these incoming bodies engage against and pushthe newly squeezed and reformed bodies off the mandrel and out of themachine. 7

Just enough stretch is put into the body stock by the reformingoperation just described to utilize the shrinkage strains present in thesubsequent drying so that the inset side walls of the body pull outstraight, the body corners holding their positions. A finishedrectangular body having rounded corners and flat straight sides (Fig. 6)results without need of molds, supports, etc. It has been found thatthis drying for a given can body shape is uniform and the exact amountand kind of reforming after being determined by trial for a given shapeof body holds good for all bodies of that shape.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the steps of the processdescribed and their order of accomplishment without departing from thespirit and scope of the invention or sacrificing all of its materialadvantages, the process hereinbefore described being merely a preferredembodiment thereof.

I claim:

1. The method of forming non-circular tubular bodies of fibrous materialand the like, which comprises subjecting a body formed in laminationsand of the desired shape, while in a green or moist condition, to areforming operation, wherein certain portions of the body wall arestretched, and thereafter drying said reformed body, after it has beenremoved from the reforming devices, whereby the drying strains restorethe said body to its original shape and size when fully dried withoutsubjecting the corner portions to strain.

2. The method of forming non-circular tubular bodies of fibrous materialand the like, which comprises subjecting a body formed in laminationsand having rounded corners and straight sides, while in a green or moistcondition, to a reforming operation which stretches the side walls ofthe body between and adjacent its corners to a degree which will, afterit has been removed from the reforming devices, counterbalance internaldrying strains present in the body wall during drying, whereby the bodysides are pulled back and the body resumes its original shape and sizewithout distortion upon being fully dried and without subjecting thecorner portions to strain.

3. The method of forming non-circular tubular bodies of fibrous materialand the like, which comprises subjecting a body formed in a pluingmeans, and thereafter drying the body, whereby the inherent internaldrying strains pull out the said predetermined wall surplus and restorethe original formed shape to the fully dried body and without subjectingthe corner 5 portions to strain.

ARTHUR A. SAALBACH.

